1. Field of the Invention
The present invention relates to a brake drive and control device for driving and controlling a brake in order to change the state of the brake from a disengaged state to an engaged state by stopping a brake drive current flowing through the brake that brakes a driven object driven in the gravity axis direction by a motor.
2. Description of Related Art
In an industrial robot, etc., having a gravity axis, a brake drive and control device for driving and controlling a brake that brakes the driven object is used in order to prevent a driven object, such as an arm, from dropping when the motor stops.
Among such brake drive and control devices, a brake drive and control device having a switching element connected to one end of the brake and a switching element connected to the other end of the brake is proposed in, for example, Japanese Patent No. 4734581 (JP4734581B). By using a brake drive and control device having two switching elements as described above, even in the event of a short circuit failure of one of the switching elements, it is possible to block the brake drive current flowing through the brake by bringing the other switching element into the off state. Consequently, even in the event of short circuit failure of one of the switching elements, the state of the brake can be changed from the disengaged state to the engaged state, and therefore, it is possible to prevent the driven object from dropping when the motor stops.
In the case where it is determined whether or not there is a short circuit failure of the switching element in the brake drive and control device having two switching elements as described above, an operation to turn on one of the switching elements as well as turning off the other switching element, and an operation to turn off one of the switching elements as well as turning on the other switching element are necessary. That is, it is necessary for the brake drive and control device having two switching elements as described above to carry out the operation to turn on and off the switching elements twice in order to detect whether or not there is a short circuit failure of the switching element, and therefore, there is a disadvantage that it requires more time to detect whether or not a short circuit of the switching element has occurred.